This is a note to let you know that I've just added the patch titled
x86/mce: Make machine check speculation protected
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-mce-make-machine-check-speculation-protected.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6f41c34d69eb005e7848716bbcafc979b35037d5 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Thu, 18 Jan 2018 16:28:26 +0100
Subject: x86/mce: Make machine check speculation protected
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit 6f41c34d69eb005e7848716bbcafc979b35037d5 upstream.
The machine check idtentry uses an indirect branch directly from the low
level code. This evades the speculation protection.
Replace it by a direct call into C code and issue the indirect call there
so the compiler can apply the proper speculation protection.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by:Borislav Petkov <bp@xxxxxxxxx>
Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Niced-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801181626290.1847@nanos
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/entry/entry_64.S | 2 +-
arch/x86/include/asm/traps.h | 1 +
arch/x86/kernel/cpu/mcheck/mce.c | 5 +++++
3 files changed, 7 insertions(+), 1 deletion(-)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1031,7 +1031,7 @@ idtentry async_page_fault do_async_page_
#endif
#ifdef CONFIG_X86_MCE
-idtentry machine_check has_error_code=0 paranoid=1 do_sym=*machine_check_vector(%rip)
+idtentry machine_check do_mce has_error_code=0 paranoid=1
#endif
/*
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -92,6 +92,7 @@ dotraplinkage void do_simd_coprocessor_e
#ifdef CONFIG_X86_32
dotraplinkage void do_iret_error(struct pt_regs *, long);
#endif
+dotraplinkage void do_mce(struct pt_regs *, long);
static inline int get_si_code(unsigned long condition)
{
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1672,6 +1672,11 @@ static void unexpected_machine_check(str
void (*machine_check_vector)(struct pt_regs *, long error_code) =
unexpected_machine_check;
+dotraplinkage void do_mce(struct pt_regs *regs, long error_code)
+{
+ machine_check_vector(regs, error_code);
+}
+
/*
* Called for each booted CPU to set up machine checks.
* Must be called with preempt off:
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-4.4/futex-prevent-overflow-by-strengthen-input-validation.patch
queue-4.4/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.4/x86-retpoline-irq32-convert-assembler-indirect-jumps.patch
queue-4.4/x86-mce-make-machine-check-speculation-protected.patch
queue-4.4/x86-pti-document-fix-wrong-index.patch
queue-4.4/x86-retpoline-hyperv-convert-assembler-indirect-jumps.patch
queue-4.4/x86-apic-vector-fix-off-by-one-in-error-path.patch
queue-4.4/x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
queue-4.4/kprobes-x86-disable-optimizing-on-the-function-jumps-to-indirect-thunk.patch
queue-4.4/x86-asm-use-register-variable-to-get-stack-pointer-value.patch
queue-4.4/x86-cpu-amd-make-lfence-a-serializing-instruction.patch
queue-4.4/x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
queue-4.4/sched-deadline-zero-out-positive-runtime-after-throttling-constrained-tasks.patch
queue-4.4/x86-retpoline-crypto-convert-crypto-assembler-indirect-jumps.patch
queue-4.4/module-add-retpoline-tag-to-vermagic.patch
queue-4.4/kprobes-x86-blacklist-indirect-thunk-functions-for-kprobes.patch
queue-4.4/x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
queue-4.4/x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
queue-4.4/x86-mm-32-move-setup_clear_cpu_cap-x86_feature_pcid-earlier.patch
queue-4.4/x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
queue-4.4/x86-retpoline-add-lfence-to-the-retpoline-rsb-filling-rsb-macros.patch
queue-4.4/x86-retpoline-optimize-inline-assembler-for-vmexit_fill_rsb.patch
queue-4.4/x86-retpoline-remove-compile-time-warning.patch
queue-4.4/x86-cpu-amd-use-lfence_rdtsc-in-preference-to-mfence_rdtsc.patch
queue-4.4/retpoline-introduce-start-end-markers-of-indirect-thunk.patch
queue-4.4/x86-retpoline-add-initial-retpoline-support.patch
queue-4.4/x86-cpu-x86-pti-do-not-enable-pti-on-amd-processors.patch
queue-4.4/x86-asm-make-asm-alternative.h-safe-from-assembly.patch